Power Take-Off Shafts or PTOs are used on agricultural vehicles such as tractors to provide power from the engine to agricultural implements. As the use of PTOs developed over the years, the industry developed a standard for two speed PTOs comprising gear speeds of 1000 and 540 rpms. Thus in order to accommodate industry standards of a particular implement relative to the appropriate gear speed, it is necessary to provide a power take-off assembly which allows quick and easy installation of a proper PTO assemblies, the output shaft has a internally splined portion adapted to axially receive the externally splined reversible power take off shaft to prevent relative rotational movement between the power take-off stub shaft and output shaft. The desired PTO shaft speed is typically determined by the configuration of the PTO shaft end inserted into the output shaft. When reversible PTO shafts are used, as in the case of the present invention, the outer end portion is adapted for engagement with the implement for the selected speed, while the configuration of the inner end portion positions a shifting mechanism against the force of a spring loaded mechanism to selectively engage the proper gear speed.
PTO shafts that are described above are often maintained in place by a locking mechanism, typically a flanged locking mechanism, and arranged externally of the output shaft to which the PTO shaft is coupled. One disadvantage of a PTO shaft and current flanged locking mechanisms is that it tends to be tedious and time consuming to install, which may require the use of an additional person or an additional hand.
Other known PTO shafts are maintained in place by an internal snap ring configured to engage an interior portion of the output shaft. Because of the high force required to compress the snap-ring for installation, special tools such as pliers are usually required to reverse the PTO shaft end. To perform the installation using a snap ring, an operator must push the PTO stub shaft to overcome the high axial force of the spring loaded shifting mechanism (e.g. spring loaded plunger), and at the same time install the snap ring.
It therefore remains desirable to provide an improved PTO stub shaft design that will provide for a quick and secure installation of the PTO stub shaft to the output shaft in a desired orientation without the use of pliers.